Senate Republicans are launching another effort to defund parts of President Barack Obama's health care law, including what their campaign chairman referred to Wednesday as "the death panel."

All 46 Republican senators signed on to a letter spearheaded by Sen. John Thune, R-S.D., that calls for a permanent delay of the health care law.

"While your recent action provides temporary relief for some, we believe that all Americans deserve permanent relief from this onerous law, so that we can adopt common-sense reforms that will actually lower costs and that Americans support," the Republicans wrote in the letter to Obama.

At a news conference unveiling the letter, Sen. Jerry Moran of Kansas announced his plan to offer amendments to the Labor-Health and Human Services-Education appropriations bill during the full Senate Appropriations markup Thursday.

"Among a series of amendments that I will offer to that bill are two that I wanted to talk about today. One, I will offer an amendment to — no money can be used to enforce the mandate on business within the Affordable Care Act, and two, I will offer an amendment that says no money can be spent in this bill to enforce the individual mandate," Moran said. In addition to chairing the National Republican Senatorial Committee, he serves as the ranking member on the Appropriations subcommittee.

"I will offer an amendment that will defund IPAB, the so-called death panel, to transfer that money to be utilized for children's health research," Moran said, adding that Republicans also "will offer an amendment to eliminate the $1.4 billion that is in the bill to fund the exchanges," citing states that decided against establishing their own health care exchanges.

The Independent Payment Advisory Board, known as IPAB, was created in the health care law as a mechanism to create cost controls for Medicare. Under the law, the panel would only be mandated to make Medicare cuts if the projected growth in the cost per beneficiary exceeded a specific target. Congress could override the cuts IPAB suggests as long as lawmakers propose reductions that save the same amount of money.

"We ought to give folks the opportunity to weigh in on the president's decision to delay the business aspect of the mandate, and secondly, if businesses are going to receive relief from this onerous record-keeping, time-consuming uncertainty then individual families, our constituents, the folks back home, ought to have that same opportunity," Moran said. "Delaying the implementation of the business mandate ought to be accompanied by a delay of the individual mandate."

Moran argued that particularly given the limited amount of money available to appropriators, they shouldn't be funding the mandates in the health care law, which he said is "falling apart."

Senators speaking at the news conference announcing the letter to Obama declined to go as far as Sen. Mike Lee, R-Utah, who has suggested that a government shutdown this fall may be a better option than accepting Democratic spending bills that fund the health care law.

"If congressional Democrats want to oppose appropriations bills without additional ObamaCare funding, shut down the government, and side with the President and big business against the American people, then it's their choice," Lee said in a Tuesday statement.

Asked to respond to those comments, Missouri Sen. Roy Blunt, an appropriator and member of the GOP leadership, said it was too early to have such a conversation given the fiscal year ends in September.

"First of all, we're a long way from September 30," Blunt said. "Secondly, what we need to see for the first time in six years is for the appropriations process to actually work: produce a bill, amend it on the floor. This idea that we only spend the amount of money we spent last year and then subject it to sequestration is not the way to do business.

"I think all those discussions are premature," Blunt said, saying that if the Senate gets back to regular order, "There'll be plenty of opportunities to amend that bill on the floor in any way that any member of the Senate wants to."

Majority Leader Harry Reid, D-Nev., has repeatedly said he would like to bring spending bills to the floor this year but that he will need Republican cooperation to do so.